Fast Gate-Based Readout of Silicon Quantum Dots Using Josephson Parametric Amplification.

Area of Science:

• Quantum Computing
• Solid-State Physics

Background:

• Silicon quantum devices are promising for large-scale quantum computing.
• Gate-based sensing of spin qubits offers scalable readout but requires improved sensitivity for fast feedback in error correction.

Purpose of the Study:

• To enhance the sensitivity and reduce integration time for gate-based sensing of silicon spin qubits.
• To enable faster single-shot readout for fault-tolerant quantum computation.

Main Methods:

• Combined radio-frequency gate-based sensing at 622 MHz with a Josephson parametric amplifier (500-800 MHz band).
• Utilized a silicon double quantum dot in a nanowire transistor for readout.

Main Results:

• Achieved a signal-to-noise ratio enabling an estimated 99.7% fidelity single-shot readout in 1 μs.
• Demonstrated a 30x speed improvement compared to systems without the Josephson parametric amplifier.
• Reduced radio-frequency power requirements while maintaining signal-to-noise ratio.

Conclusions:

• The integration of Josephson parametric amplifiers significantly accelerates spin qubit readout in silicon.
• Achieved readout speeds meet requirements for fault-tolerant quantum computing.
• Identified noise sources and outlined pathways for further readout speed enhancement.